<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <div id="app">
    姓：<input v-model="firstName" type="text"><br>
    名：<input v-model="lastName" type="text"><br>
    <p>姓名：{{fullName}}</p>
    <button @click="changeName()">修改姓名</button>
  </div>
  <script src="js/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        firstName:"刘",
        lastName:"备"
      },
      computed: {
        fullName:{
          get(){
            return this.firstName+this.lastName
          },
          set(value){
            console.log(value);
            this.firstName = value.slice(0,1)
            this.lastName = value.slice(1)
          }
        }
      },
      methods: {
        changeName(){
          this.fullName = "吕小布"
        }
      }
    })
  </script>
</body>
</html>